class Solution {
    public int findTargetSumWays(int[] nums, int target) {
        int sum=0;
        for (int i = 0; i <nums.length ; i++) sum+=nums[i];
        if(target>sum) return 0;//没有方案
        if((target+sum)%2==1) return 0;//此时没有方案

        int bagSize=(target+sum)/2;
        int[] dp =new int[bagSize+1];
        dp[0]=1;
        for (int i = 0; i < nums.length; i++) {
            for (int j = bagSize; j >= nums[i]; j--) {
                dp[j] += dp[j - nums[i]];
            }
        }
        return dp[bagSize];
    }
}